from pythonds.basic.stack import Stack

s = Stack()
print(s.isEmpty())  # True
s.push(5)
s.push('dog')
print(s.peek())  # dog
s.push(True)
print(s.size())  # 3
print(s.isEmpty())  # False
s.push(7.5)
print(s.pop())  # 7.5
print(s.pop())  # True
print(s.size())  # 2
